Loom Owning Households (%)
4.5 Analyses of responses to questionnaire constructed for subjective evaluation of the impact of illumination and
4.5.7 Spearman’s correlation coefficient (r) and Coefficient of Determination (CoD, r 2 ) for correlation of illumination level and
corresponding subjective responses
Subjective responses to question numbers 1, 13, 14 and 25 in the questionnaire (Table 4.24) on the impact of illumination revealed that there was significant (p < 0.001) indirect correlation between illumination and the psychological discomfort factors such as effect on work efficiency in the existing lighting, visual environment at workstation, discomfort due to glare, rating of perceived exertion(RPE) due to illumination ( r = - 0.09, p < 0.001 for Jan; r = - 0.09, p < 0.001 for Feb; r = -0.07, p < 0.001 for Mar; r = - 0.07, p < 0.001 for Apr; r = - 0.07, p < 0.001 for May; r = - 0.07, p < 0.001 for Jun; r = - 0.06, p < 0.001 for Jul; r = - 0.06, p < 0.001 for Aug; r = - 0.07, p < 0.001 for Sep; r = - 0.06, p < 0.001 for Oct; r = - 0.08, p < 0.001 for Nov; r = - 0.09, p < 0.001 for Dec).
Calculation of coefficient of determination (CoD ; r2) showed variable trend of shared variance, thereby indicating differential level of dependence of effect on work efficiency in the existing lighting, visual environment at workstation, discomfort due to glare, rating of perceived exertion(RPE) due to illumination (r2=0.008 for Jan; r2=0.008 for Feb; r2=0.005 for Mar; r2=0.005 for Apr; r2=0.005 for May; r2=0.005 for Jun;
r2=0.004 for Jul; r2=0.005 for Aug; r2=0.005 for Sep; r2=0.004 for Oct; r2=0.006 for Nov;
r2=0.008 for Dec).
Table 4.24 Month wise representation of correlation properties (r and r2) showing the significance of difference between illumination and questions in the questionnaire
Month Jan Feb Mar Apr May Jun
Parameter r r2 r r2 r r2 r r2 r r2 r r2
Q.1,13,14,25 -0.92
***
0.008 -0.09
***
0.009 -0.07
***
0.005 -0.07
***
0.005 -0.07
***
0.005 -0.07
***
0.005
Q.2,3,4,5,6, -0.35
***
0.119 -0.34
***
0.119 -0.32
***
0.104 -0.33
***
0.106 -0.33
***
0.108 -0.33
***
0.106
Q.7,8,9,10,11,12 -0.49
***
0.242 -0.49
***
0.242 -0.49
***
0.236 -0.49
***
0.237 -0.49
***
0.238 -0.49
***
0.237
Q.15,16,17,18 0.61
***
0.376 0.61
***
0.376 0.58
***
0.340 0.59
***
0.343 0.59
***
0.350 0.59
***
0.343
Q.19,20,21,22,23,24 -0.75
***
0.565 -0.75
***
0.566 -0.73
***
0.539 -0.73
***
0.539 -0.74
***
0.545 -0.73
***
0.539
Month Jul Aug Sep Oct Nov Dec
Parameter r r2 r r2 r r2 r r2 r r2 r r2
Q.1,13,14,25 -0.06
***
0.004 -0.06
***
0.004 0.068
***
0.005 -0.06
***
0.004 -0.06
***
0.004 0.068
***
0.005
Q.2,3,4,5,6, -0.31
***
0.096 -0.31
***
0.099 -0.32
***
0.102 -0.31
***
0.093 -0.31
***
0.109 -0.32
***
0.118
Q.7,8,9,10,11,12 -0.47
***
0.223 -0.48
***
0.227 -0.48
***
0.232 -0.47
***
0.219 -0.48
***
0.236 -0.48
***
0.242
Q.15,16,17,18 0.56
***
0.310 0.57
***
0.320 0.58
***
0.331 0.56
***
0.302 0.57
***
0.351 0.58
***
0.375
Q.19,20,21,22,23,24 -0.72
***
0.520 -0.73
***
0.528 -0.73
***
0.534 -0.72
***
0.511 -0.73
***
0.550 -0.73
***
0.564
Q1 to Q25 represent the questions in the questionnaire for subjective rating of workplace illumination, where Q1 rates effect on work efficiency, Q2 headache, Q3 fatigue due to light, Q4 eye irritation, Q5 redness of eyes, Q6 water falling from eye, Q7 neck pain, Q8 lower back pain, Q9 thigh pain, Q10 waist pain, Q11 ankle / feet pain, Q12 shoulder pain, Q13 visual environment at work station, Q14 discomfort due to glare, Q15 sensation of light on loom, Q16 sensation of light around loom, Q17 illumination satisfaction level on loom, Q18 effect of light on job performance, Q19 mental demand, Q20 physical demand, Q21 temporal demand, Q22 performance, Q23 effort, Q24 frustration and Q25 RPE due to illumination. Questions were grouped for better apprehension regarding aspect of perception and corresponding subjective responses. ‘r’ represents spearman’s correlation coefficient and ‘r2’ represents coefficient of determination (CoD), *** against an ‘r’ value indicates significant correlation at P < 0.001 between existing workplace illumination and mentioned questions of the questionnaire against the corresponding ‘r’
Subjective responses to Question numbers 2 – 6 in the questionnaire on the impact of illumination revealed significant (p < 0.001) inverse correlation between illumination and the physiological discomfort factors such as headache due to existing lighting conditions, fatigue due to light, eye irritation, redness of eyes, water falling from eye ( r
= -0.35, p < 0.001 for Jan; r = -0.34, p < 0.001 for Feb; r = -0.32, p < 0.001 for Mar; r = -0.33, p < 0.001 for Apr; r = -0.33, p < 0.001 for May; r = -0.33, p < 0.001 for Jun; r = - 0.31, p < 0.001 for Jul; r = -0.31, p < 0.001 for Aug; r = -0.32, p < 0.001 for Sep; r = - 0.30, p < 0.001 for Oct; r = -0.33, p < 0.001 for Nov; r = -0.34, p < 0.001 for Dec).
Calculation of coefficient of determination (CoD ; r2) showed variable trend of shared variance, thereby indicating differential level of dependence of effect on headache due to existing lighting conditions, fatigue due to light, eye irritation, redness of eyes, water falling from eye (r2 = 0.119 for Jan; r2 = 0.119 for Feb; r2 = 0.104 for Mar; r2 = 0.106 for Apr; r2 = 0.108 for May; r2 = 0.106 for Jun; r2 = 0.096 for Jul; r2 = 0.099 for Aug; r2 = 0.102 for Sep; r2 = 0.093 for Oct; r2 = 0.109 for Nov; r2 = 0.118 for Dec).
Subjective responses to Question numbers 7 – 12 in the questionnaire on the impact on illumination revealed significant (p < 0.001) inverse correlation between illumination and the physiological discomfort factors such as neck pain due to existing lighting conditions, lower back pain, thigh pain, waist pain, ankle/ feet pain and shoulder pain ( r = - 0.49, p < 0.001 for Jan; r = - 0.49, p < 0.001 for Feb; r = - 0.49, p < 0.001 for Mar; r = - 0.49, p < 0.001 for Apr; r = - 0.49, p < 0.001 for May; r = - 0.49, p < 0.001 for Jun; r = - 0.47, p < 0.001 for Jul; r = - 0.48, p < 0.001 for Aug; r = - 0.48, p < 0.001 for Sep; r = - 0.47, p < 0.001 for Oct; r = - 0.49, p < 0.001 for Nov; r = - 0.49, p < 0.001 for Dec).
Calculation of coefficient of determination (CoD ; r2) showed variable trend of shared variance, thereby indicating differential level of dependence of neck pain due to existing lighting conditions, lower back pain, thigh pain, waist pain, ankle/ feet pain and shoulder pain (r2 = 0.242 for Jan; r2 = 0.242 for Feb; r2 = 0.236 for Mar; r2 = 0.237 for Apr; r2 = 0.238 for May; r2 = 0.237 for Jun; r2 = 0.223 for Jul; r2 = 0.227 for Aug; r2 = 0.232 for Sep; r2 = 0.219 for Oct; r2 = 0.236 for Nov; r2 = 0.242 for Dec).
Subjective responses to question numbers 15 – 18 in the questionnaire on the impact of illumination revealed highly significant (p < 0.001) direct correlation between illumination and the physiological discomfort factors such as sensation of light on loom, sensation of light around loom, illumination satisfaction level on loom and effect of light on job performance ( r = + 0.61, p < 0.001 for Jan; r = + 0.61, p < 0.001 for Feb;
r = + 0.58, p < 0.001 for Mar; r = + 0.59, p < 0.001 for Apr; r = + 0.59, p < 0.001 for May; r = + 0.59, p < 0.001 for Jun; r = + 0.56, p < 0.001 for Jul; r = + 0.57, p < 0.001 for Aug; r = + 0.58, p < 0.001 for Sep; r = + 0.55, p < 0.001 for Oct; r = + 0.59, p <
0.001 for Nov; r = + 0.61, p < 0.001 for Dec).
Calculation of coefficient of determination (CoD ; r2) showed variable trend of shared variance, thereby indicating differential level of dependence of sensation of light on loom, sensation of light around loom, illumination satisfaction level on loom and effect of light on job performance (r2 = 0.376 for Jan; r2 = 0.376 for Feb; r2 = 0.340 for Mar; r2 = 0.343 for Apr; r2 = 0.350 for May; r2 = 0.343 for Jun; r2 = 0.311 for Jul; r2 = 0.320 for Aug; r2 = 0.331 for Sep; r2 = 0.302 for Oct; r2 = 0.351 for Nov; r2 = 0.375 for Dec).
Subjective responses to question numbers 19 – 24 in the questionnaire on the impact of illumination revealed highly significant (p < 0.001) inverse correlation between illumination and the psychological discomfort factors such as mental demand, physical demand, temporal demand, performance, effort and frustration ( r = - 0.75, p <
0.001 for Jan; r = - 0.75, p < 0.001 for Feb; r = - 0.73, p < 0.001 for Mar; r = - 0.73, p <
0.001 for Apr; r = - 0.74, p < 0.001 for May; r = - 0.73, p < 0.001 for Jun; r = - 0.72, p <
0.001 for Jul; r = - 0.73, p < 0.001 for Aug; r = - 0.73, p < 0.001 for Sep; r = - 0.71, p <
0.001 for Oct; r = - 0.74, p < 0.001 for Nov; r = - 0.75, p < 0.001 for Dec).
Calculation of coefficient of determination (CoD ; r2) showed variable trend of shared variance, thereby indicating differential level of dependence of effect on work efficiency in the existing lighting, visual environment at workstation, discomfort due to glare, rating of perceived exertion(RPE) due to illumination (r2 = 0.565 for Jan; r2 = 0.566 for Feb; r2 = 0.539 for Mar; r2 = 0.539 for Apr; r2 = 0.545 for May; r2 = 0.539 for Jun; r2 = 0.520 for Jul; r2 = 0.528for Aug; r2 = 0.534 for Sep; r2 = 0.511 for Oct; r2 = 0.550 for Nov; r2 = 0.564 for Dec).